High voltage DC power supply

Abstract

A DC power supply for a traveling wave tube having cathode, collector and helix electrodes responds to a DC power source and a high frequency switching source. A switch controlled by the switching source is opened and closed at a fixed frequency and variable duty cycle determined by the helix-cathode voltage. A flyback choke is connected to the switch and DC power supply so current flows between the power source via the choke to the switch and a series resonant circuit while the switch is closed. First and second capacitors in separate branch circuits of the resonant circuit are respectively connected to first and second AC to DC converter and voltage multiplier stacks; each multiplier in the stacks includes a pair of branches with oppositely poled plural signal switching diodes and a capacitor. The cathode and helix are respectively connected to output terminals of the first and second stacks, while the collector is connected to a terminal between the first and second stacks. The resonant circuit is connected with the switch, flyback choke and voltage multipliers so that while the switch is closed a half-wave rectified current hump at the resonant circuit resonant frequency flows in the resonant circuit and a ramping current having a first polarity direction flows in the choke. A ramping current having a second polarity direction flows in the choke and resonant circuit while the switch is open.

I claim: 
     
       1. A DC power supply responsive to a relatively low voltage DC power source and a high frequency switching source comprising capacitive and diode AC to DC converter means for deriving a DC output voltage; a switch controlled by the switching source to open and closed states; a flyback choke connected in series with the switch and the DC power source so current flows between terminals of the power source via the choke and switch while the switch is closed; resonant circuit means connected in circuit with the switch, the flyback choke and the AC to DC converter means so that each time the switch is closed (a) a half wave rectified current waveform having a duration determined by the resonant frequency of the resonant circuit means flows in the resonant circuit means and (b) a first current component having first polarity direction flows in the choke, and while the switch is open a second current component having a second polarity direction flows in the choke and the resonant circuit means, the AC to DC converter means responding to each half wave rectified current waveform to derive the DC output voltage and includes voltage multiplier means for deriving the DC output voltage as a high voltage DC and wherein the voltage multiplier means includes plural high speed signal switching diodes each having a recovery time that is a small fraction of the duration of each half wave rectified current waveform. 
     
     
       2. The DC power supply of claim 1 wherein the voltage multiplier means includes plural stacked voltage multiplier modules, each including a pair of oppositely poled diodes and a capacitor connected between oppositely poled electrodes of the pair of diodes, and means for capacitively coupling current in opposite directions to different ones of the stacked modules from a common terminal of the resonant circuit means. 
     
     
       3. The DC power supply of claim 2 further including capacitive means connected to a high voltage output terminal of the stacked modules for providing a return path for the current of the resonant circuit means flowing in the stacked modules. 
     
     
       4. The DC power supply of claim 3 wherein the capacitive means includes means for establishing a capacitive path for the half wave rectified current waveform between each high voltage output terminal and a low voltage terminal of the power supply source. 
     
     
       5. A DC power supply responsive to an AC current source having a frequency of at least 100 kiloHertz comprising plural stacked AC to DC converter and voltage multiplier modules each including a pair of oppositely poled unidirectional diodes, each of said diodes being a signal switching diode having a recovery time that is a small fraction of a cycle of the frequency of the AC source, a capacitor connected between oppositely poled electrodes of said diodes, and means for capacitively coupling current from a common terminal of the AC current source to first and second of the stacked modules so that current simultaneously flows from the common terminal through a first capacitor to a first module and through a second capacitor to a second module, the coupling being such that the current flowing through the first capacitor to the first module does not flow through the second module and the current flowing through the second capacitor to the second module does not flow through the first module. 
     
     
       6. The DC power supply of claim 5 further including capacitive means connected with an output terminal of the stacked modules for providing a return path for the current of the AC current source back to the AC current source. 
     
     
       7. A DC to DC converter responsive to a relatively low voltage DC power source and a high frequency switching source comprising rectifier means for deriving a DC output voltage, a switch controlled by the switching source to open and closed states, a flyback choke connected in series with the switch and the DC power source so current flows between terminals of the power source via the choke and switch while the switch is closed, resonant circuit means connected in circuit with the switch, the flyback choke and the rectifier means so that each time the switch is closed (a) a half wave rectified current waveform having a duration determined by the resonant frequency of the resonant circuit means flows in the resonant circuit means and (b) a first current component having a first polarity direction flows in the choke, and while the switch is open a second current component having a second polarity direction flows in the choke and the resonant circuit means, the rectifier means responding to each half wave rectified current waveform to derive the DC output wherein the rectifier means feeds a voltage multiplier means including plural high speed signal switching diodes each of said diodes having a recovery time that is a small fraction of the duration of each current hump. 
     
     
       8. In combination, an electron tube having first, second and third electrodes, and a high voltage DC power supply responsive to a relatively low voltage DC power source, and a high frequency switching source for deriving pulses having variable durations; a switch controlled by the switching source to open and closed states; a flyback choke connected in series with the switch and the DC power source so current flows between terminals of the power source via the choke and switch while the switch is closed; resonant circuit means having a resonant frequency, the resonant circuit means being responsive to current flowing from the power source through the choke while the switch is closed for deriving a current having a half wave sinusoidal waveform each time the switch is closed; the choke being connected to the source, resonant circuit means and switch so that the amount of energy stored in the choke each time the switch is closed is determined by the duration of the pulses and the amplitude of each half wave sinusoidal waveform is determined by the amount of energy stored in the choke; the duration of each half wave sinusoidal waveform being determined by the resonant frequency; the resonant circuit means including means for converting the current having a half wave sinusoidal waveform to DC voltages supplied to the electrodes, and means responsive to voltage between a pair of electrodes of said tube for controlling the durations of said pulses to maintain the voltage between the pair of electrodes substantially constant. 
     
     
       9. The combination of claim 8 wherein the resonant circuit means includes an inductor having a first terminal connected between the choke and switch and a second terminal connected to first electrodes of first and second capacitors connected in separate branch circuits, the first and second capacitors having second electrodes respectively connected to first and second AC to DC converter and voltage multiplier stacks included in said means for converting, each AC to DC converter and voltage multiplier in said stacks including a pair of oppositely poled unidirectional diodes and a capacitor connected between oppositely poled electrodes of the pair of diodes, the first and second stacks being stacked together, the first and third electrodes of the tube being connected to opposite polarity terminals of the first and second stacks, the second electrode of the tube being connected to a terminal between the first and second stacks. 
     
     
       10. The combination of claim 8 wherein the switching source includes means for deriving constant frequency variable duty cycle pulses. 
     
     
       11. A DC power supply responsive to an AC current source comprising plural stacked AC to DC converter and voltage multiplier modules each including a pair of oppositely poled unidirectional diodes and a capacitor connected between oppositely poled electrodes of the diodes, means for capacitively coupling current from a common terminal of the AC current source to first and second of the stacked modules so that current flows from the common terminal through a first branch including a first capacitor to a first module and through a second branch including a second capacitor to a second module, the coupling being such that the current flowing through the first branch to the first module does not flow through the second module and the current flowing through the second branch to the second module does not flow through the first module, and capacitive means connected with an output terminal of the stacked modules for providing a return path for the current of the AC current source back to the AC current source. 
     
     
       12. The power supply of claim 11 wherein each of the diodes has a recovery time that is a small fraction of a cycle of the AC current source. 
     
     
       13. The power supply of claim 12 wherein the small fraction is less than 0.5 percent. 
     
     
       14. The power supply of claim 12 wherein the small fraction is about 0.2 percent. 
     
     
       15. A DC power supply responsive to an AC current source having a frequency of at least 100 kiloHertz comprising plural stacked AC to DC converter and voltage multiplier modules each including a pair of oppositely poled unidirectional branches and a capacitor connected between oppositely poled electrodes of diodes of the branches, and means for capacitively coupling current from a common terminal of the AC current source to first and second of the stacked modules so that current flows simultaneously from the common terminal through a first branch including a first capacitor to a first module and through a second branch including a second capacitor to a second module, the coupling being such that the current flowing through the first branch to the first module does not flow through the second module and the current flowing through the second branch to the second module does not flow through the first module, the diodes of the branches having a recovery time that is a small fraction of a cycle of the AC current source. 
     
     
       16. The power supply of claim 15 wherein the small fraction is less than 0.5 percent. 
     
     
       17. The power supply of claim 15 wherein the small fraction is about 0.2 percent. 
     
     
       18. The power supply of claim 15 wherein the recovery time is about 4 nanoseconds. 
     
     
       19. A DC power supply responsive to an AC current source comprising plural stacked AC to DC converter and voltage multiplier modules each including a pair of oppositely poled unidirectional diodes and a capacitor connected between oppositely poled electrodes of the diodes, and means for capacitively coupling current from a common terminal of the AC current source to first and second of the stacked modules so that current flows simultaneously from the common terminal through a first branch including a first capacitor of a first module and through a second branch including a second capacitor of a second module, the first module being connected to a first ungrounded DC output terminal adapted to be connected to a first DC load, the second module being connected to a second ungrounded DC output terminal adapted to be connected to a second DC load, the first and second modules being connected to the common terminal and the load terminals so the currents flowing between the common terminal and the first and second output terminals maintain the first and second output terminals at different DC voltage levels relative to each other and ground. 
     
     
       20. The power supply of claim 19 wherein each of said diodes has recovery time that is a small fraction of a cycle of the AC current source. 
     
     
       21. The power supply of claim 20 wherein the small fraction is less than 0.5 percent. 
     
     
       22. The power supply of claim 20 wherein the small fraction is abut 0.2 percent.